As shown in FIG. 1, a trolley system according to the related art has judged whether or not succession has been conducted based on manipulation timings of switches 6 each provided in a chain dog 4 and a hanger dog 5 when a hanger 1 is succeeded from a pre-process driving chain 2 to a post-process driving chain 3.
However, in a technology of judging the succession through the manipulation timing of the switches according to the related art, the judgment on the succession will be disturbed due to a malfunction, so a timing delay of the switches and non-conducting of the succession may occur, which may separate the hanger from the driving chain.